Contact probe, measuring pad used for the contact probe, and method of manufacturing the contact probe

ABSTRACT

There is provided a contact probe that is smaller than 50 μm in a pitch between a signal electrode and a ground electrode and can correctly conduct a high-speed high-frequency measurement, a measuring pad used for the contact probe, and a method of manufacturing the contact probe. The contact probe includes: a tip member having a signal electrode  10   a  and a ground electrode  11   a  that are put into contact with an object to be measured; and a coaxial cable  1  having a core  1   b  electrically connected to the signal electrode  10   a  and an outer covering conductor la electrically connected to the ground electrode  11   a , wherein the tip member is formed on a printed wiring board  2 , and wherein the signal electrode  10   a  and the ground electrode  11   a  are constructed of fine coplanar strip lines formed on an insulating board  2   a.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a contact probe used for measuring andevaluating the high-speed high-frequency characteristics of asemiconductor integrated circuit, a package for a semiconductorintegrated circuit, a printed circuit board, and the like, and ameasuring pad used for the contact probe, and a method for manufacturingthe contact probe.

2. Description of the Related Art

In recent years, semiconductor integrated circuit (LSI) chips inelectronic devices have been remarkably improved in the performance.With this, a clock frequency ranging from 3 GHz to 5 GHz is becoming astandard for a CPU. Further, a transmission speed in the packagingsystem of an electronic device reaches 500 Mbps to 1 Gbps although thegrowth of improvement in performance is slowing.

Further, to increase the speed and to decrease the size of an electronicdevice, a high-density packaging technology has received attention andthe research and development of the high-density packaging technologyhave been actively conducted. For example, in “Fabrication ofHigh-Density Wiring Interposer for 10 GHz 3D Packaging Using aPhotosensitive Multiblock Copolymerized Polyimide” (Katsuya Kikuchi,Eun-Sil Jung, Shigemasa Segawa, Yoshihiko Nemoto, Hiroshi Nakagawa,Kazuhiko Tokoro, and Masahiro Aoyagi; Extended Abstracts of 2003International Conference on Solid State Devices and Materials, pp.382–383, 2003) is disclosed a report on an integrated circuit interposerthat can be connected to fine bumps of a minimum pitch of 20 μm so as tolaminate and package a three-dimensional semiconductor integratedcircuit chip. Here, the interposer means a kind of LSI package used formounting an LSI chip on a circuit board.

Under the above-described circumstances, a high-frequency contact probedeveloped for ultra-high speed signal measurement and evaluation in amicrowave region has been conventionally used for high-speedhigh-frequency characteristics in LSIs, chip mounting packages, circuitboards, and the like.

However, an inter-electrode pitch (a pitch between a signal electrodeand a ground electrode) at the tip of the probe that is conventionallywidely used is approximately 100 μm even if it is the finest.

Further, the finest inter-electrode pitch of a commonly available probe(made by GGB Co., (U.S.A.) or Cascade Microtech Corp. (U.S.A.) is 50 μm.

Because even a minimum inter-electrode pitch of a conventionalhigh-frequency contact probe is 50 μm, the characteristics of theinterposer for the integrated circuit having a fine pitch of 20 μmcannot be directly evaluated. Hence, it has been desired that a contactprobe having a smaller inter-electrode pitch will be developed.

SUMMARY OF THE INVENTION

The present invention has been made under the above-describedcircumstances. The object of the invention is to provide a contact probethat is smaller than 50 μm in a pitch between a signal electrode and aground electrode and can correctly conduct a high-speed high-frequencymeasurement, a measuring pad used for the contact probe, and a method ofmanufacturing the contact probe.

A contact probe in accordance with the present invention that isinvented so as to solve the above problem is a contact probe that isused for measuring and evaluating high-speed high-frequencycharacteristics and includes: a tip member having a signal electrode anda ground electrode that are put into contact with an object to bemeasured; and a coaxial cable having a core electrically connected tothe signal electrode and an outer covering conductor electricallyconnected to the ground electrode, and is characterized in that the tipmember is formed on a printed wiring board and in that the signalelectrode and the ground electrode are constructed of fine coplanarstrip lines formed on the board.

Here, it is preferable that an inter-electrode pitch between the signalelectrode and the ground electrode be formed in a size of from 10 μm ormore to 50 μm or less.

In this manner, a tip member including the signal electrode and theground electrode that are put into contact with an object to be measuredis made of a printed wiring board. Hence, a circuit pattern formingtechnology used for a printed wiring board can be employed and hence theinter-electrode pitch between the signal electrode and the groundelectrode can be made smaller than 50 μm.

As a result, the characteristics of an interposer for an integratedcircuit having a fine pitch of, for example, 20 μm can be evaluated withease and with high accuracy.

Further, it is preferable that a positioning guide line showing thecenter position of the signal electrode and the ground electrode beformed on the reverse surface of the board on which the signal electrodeand the ground electrode are formed.

By forming the positioning guide line in this manner, it is possible toposition the tip of the probe with ease.

Still further, it is preferable that the tip member has a ground lineformed opposite to the ground electrode across the signal electrode.

By forming the tip member in this manner, it is possible to stabilizethe impedance of a signal line in the signal electrode at a low leveland hence to measure a signal from a contact electrode with moreaccuracy.

Still further, it is preferable that the ground electrode is formed tothe same tip position as the signal electrode, and that the ground lineis formed in a length shorter than the tip position of the signalelectrode.

By forming the ground electrode and the ground line in this manner, itis possible to prevent the ground line from interfering with (being putinto contact with) an object to be measured when the contact electrodesare put into contact with the object to the measured.

Still further, it is preferable that a measuring pad disposed betweenthe contact probe and an object to be measured includes: the firstbonding pad that has one of the signal electrode and the groundelectrode printed thereon so as to be put into contact with each other;and the second bonding pad that has the other of the signal electrodeand the ground electrode printed thereon so as to be put into contactwith each other, and is characterized in that the first bonding pad isformed along the direction of an inter-electrode pitch between thesignal electrode and the ground electrode in a width of 1.5 to 3 timesas large as the inter-electrode pitch, and in that the second bondingpad is formed in a width of 0.5 times or less of the inter-electrodepitch, and in that a pitch between the first bonding pad and the secondbonding pad is 0.5 times or less of the inter-electrode pitch.

Because the first bonding pad is formed in a large size in this manner,it is possible to find the position of the first bonding pad at the timeof observing it with a microscope and hence to easily find a gap betweenthe first bonding pad and the second bonding pad by searching the gapwith attention concentrated along the contour line of the first bondingpad. Further, because the width of the first bonding pad is formed in alarger size than the inter-electrode pitch of the probe, even if the tipof the contact probe is slightly shifted in position when it is pressedonto the measuring pad, it is possible to put the tip of the contactprobe (contact electrode) into correct contact with the pad formeasurement.

Still further, a method of manufacturing a contact probe in accordancewith the present invention is a method of manufacturing a contact probeused for measuring and evaluating high-speed high-frequencycharacteristics, and is characterized by the steps of: manufacturing aprinted wiring board on which wirings of a signal electrode and a groundelectrode, which are put into contact with an object to be measured, areformed; and electrically connecting the signal electrode to the core ofa coaxial cable and electrically connecting the ground electrode to theouter covering conductor of the coaxial conductor.

In this manner, a tip member having a signal electrode and a groundelectrode, which are put into contact with an object to be measured, aremade of the printed wiring board. Hence, it is possible to form aninter-electrode pitch between the signal electrode and the groundelectrode with ease and precision by a circuit pattern formingtechnology used for the printed wiring board.

This printed wiring board can be formed by the steps of: roughening andcatalyzing the surface of an insulating resin board; forming anonelectrolytic copper-plated film over the whole surface of theroughened and catalyzed board after the above-described step; forming aresist pattern for forming a fine wiring by a lithography process afterthe step of forming the film; forming an electrolytic copper-plated filmon the nonelectrolytic copper-plated film, on which the resist patternis not formed, after the step of forming a resist pattern for forming afine wiring; removing the resist pattern after the step of forming anelectrolytic copper-plated film to expose the nonelectrolyticcopper-plated film and the electrolytic copper-plated film, which becomecopper fine wirings; and etching off an unnecessary nonelectrolyticcopper except for the copper fine wirings after the above-describedstep.

Still further, in the step of manufacturing the printed wiring board, aninter-electrode pitch between the signal electrode and the groundelectrode is formed in a size of from 10 μm or more to 50 μm or less.

According to this method, it is possible to manufacture a contact probethat can be pressed onto a fine pitch of from 10 μm or more to 50 μm orless, which is formed on a semiconductor integrated circuit, a packagefor a semiconductor integrated circuit, a printed circuit board, and thelike.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view and a side view showing the whole of a contactprobe in accordance with the present invention;

FIG. 2 shows a state where the contact probe in FIG. 1 is assembled, andFIGS. 2A to 2C are plan views and FIG. 2D is a front view;

FIG. 3 is a plan view showing another embodiment of the tip of thecontact probe in FIG. 1;

FIG. 4 shows a process of manufacturing a printed circuit board used forthe tip of the probe shown in FIG. 2 and FIG. 3;

FIG. 5 is a plan view of a measuring pad disposed between an object tobe measured and the contact probe in FIG. 1;

FIG. 6 schematically shows a chip mounting package (board) used in anembodiment;

FIG. 7 is a view useful in explaining the outline of an embodiment and agraph showing a measurement result; and

FIG. 8 is a view useful in explaining the outline of a comparativeexample and a graph showing a measurement result.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereafter, the preferred embodiments of the present invention will bedescribed on the basis of the drawings. FIG. 1 is a plan view and a sideview showing the whole of a contact probe in accordance with the presentinvention. FIGS. 2A to 2D are views showing a state where the contactprobe in FIG. 1 is assembled, and FIGS. 2A to 2C are plan views and FIG.2D is a front view.

As shown in the plan view in FIG. 1A and in the side view in FIG. 1B,this contact probe 100 is constructed of a semi-rigid type coaxial cablehaving a predetermined hardness and irreversibility to bending, aprinted wiring board 2 as a probe tip member, which is mounted on thetip of the coaxial cable 1, and an attachment 3 to which the other endof the coaxial cable 1 is attached.

On the printed wiring board 2, contact electrodes (signal electrode,ground electrode) that are put into contact with an object to bemeasured are formed as fine coplanar strip wirings. That is, the signalelectrode and the ground electrode that are contact electrodes areformed as copper fine wirings and are arranged in parallel on the sameplane of the board.

Further, an electric signal inputted (or detected) from the contactelectrode is configured to be outputted to the female coaxial connector3 a of the attachment 3 via the coaxial cable 1.

Here, the female coaxial connector 3 a is connected to a coaxial cable(not shown) with male coaxial connectors. The cable is used forconnecting to a high-frequency measuring device (not shown). Mountingopenings 3 b formed in the attachment 3 are used for mounting a contactprobe 100 on a probe inching mechanism (not shown) with bolts or thelike.

Next, a probe tip will be described on the basis of FIG. 2. As shown ina plan view in FIG. 2A, in the printed wiring board 2, ground lines 11are formed across a signal line 10 and a cutout space 4 on an insulatingresin board 2 a.

Further, in a contact portion to be put into contact with an object tobe measured, which is shown in an partial enlarged view in FIG. 2A, thecontact electrodes (signal electrode 10 a, ground electrode 11 a) areformed in a width of 10 μm, respectively, and a pitch between theelectrodes is formed in 20 μm. Here, as for the probe tip shown in FIG.2A, a construction may be also employed in which the probe tip isflipped from top to bottom, that is, the ground electrode 11 a and thesignal electrode 10 a are opposite to each other in position.

Further, on the reverse surface of the board 2 on which two electrodelines of the signal line 10 a and the ground electrode 11 a are formed,a positioning guide line (not shown) is shown and formed at the centerof the two electrode lines. That is, at the time of measurement, theprobe tip is positioned by using this positioning guide line. Thispositioning guide line can be formed by the same method as a method offorming the signal electrode 10 a and the ground electrode 11 a, or byscratching out a groove.

On the other hand, as shown in FIG. 2B, the tip of the coaxial cable 1is formed such that its core 1 b is protruded from its outer coveringconductor 1 a. As described above, the coaxial cable 1 is a semi-rigidtype cable and, as shown in FIG. 2D, the outer covering is the conductor(referred to as an outer covering conductor) 1 a connected to the groundand the core 1 b to become a signal line is formed across an insulator 1c.

When the coaxial cable 1 is connected to the printed wiring board 2, theouter covering conductor 1 a of the coaxial cable 1 is fitted in thecutout space 4 of the printed wiring board 2. That is, the cutout space4 serves as a guide for mounting the coaxial cable 1.

At this time, there is brought about a state where the core 1 b is puton the mounting electrode 10 b of the signal line 10 formed on theprinted wiring board 2.

As shown in FIGS. 2C and 2D, the outer covering conductor 1 a and themounting electrode 11 b of the ground line 11 are electrically connectedto each other by solder 12 and the core 1 b and the mounting electrode10 b of the signal line 10 are electrically connected to each other bysolder 12, whereby the contact probe 100 is completed.

In this regard, in the contact probe in accordance with the presentinvention, the form of the above-described probe tip, that is, theprinted wiring board 2 is not necessarily limited to the form shown inFIG. 2.

For example, as shown in FIG. 3, a ground line 11 c connected to themounting electrode 11 b may be formed. Here, in FIG. 3, FIG. 3A is aplan view showing the whole of the printed wiring board 2 and FIG. 3B isa partial enlarged view in FIG. 3A and is a plan view showing theperiphery of the contact portion.

The printed wiring board 2 shown in FIG. 3 is different only in theperiphery of the contact portion from the embodiment shown in FIG. 2and, as described above, the ground line 11 c is formed opposite to theground electrode 11 a across the signal electrode 10 a. Here, the pitchbetween the signal electrode 10 a and the ground line 11 c is 20 μm aslarge as the pitch between the contact electrodes.

With this, the impedance of the signal line in the signal electrode 10 acan be reduced to a small value with stability and hence a measurementon a signal from the contact electrode can be made with high accuracy.

Further, as shown in FIG. 3B, the tip of the signal electrode 10 a,which is the contact electrode, and a position of the tip of the groundelectrode 11 a are formed to the same length. On the other hand, aposition of the tip of the ground line 11 c is formed to be insidecompared to the tips of the signal electrode 10 a and the groundelectrode 11 a.

That is, when the contact electrode comes into contact with an object tobe measured, the ground line 11 c does not interfere with (come intocontact with) the object to be measured.

When the ground line 11 c is formed such that its tip position is thesame as the tip position of the ground electrode 11 a, the contact probecan be also suitably used as a ground-signal-ground (GSG) type contactprobe that is suitable for being in contact with a line of a coplanerwaveguide (CPW) structure.

In the manufacturing of the printed wiring board 2 at the tip of thecontact probe 100, for example, a semi-additive method (method offorming wirings by applying a copper plating to an insulating board) canbe suitably used. A manufacturing process of the printed wiring board 2will be described with reference to FIG. 4.

FIG. 4 shows a process of manufacturing a printed circuit board used forthe tip of a probe shown in FIG. 2 or FIG. 3.

First, an insulating resin board 2 a such as FR-4 (epoxy resin laminatedboard made of heat-resistant glass material), BT resin (made byMitsubishi Gas Chemical Company, Inc.), liquid crystal polymer, Teflon,polyimide, or the like is prepared and its surface is subjected to aroughening and catalyzing processing (FIG. 4A). Then, a nonelectrolyticcopper-plated film 20 is formed over the whole surface of the roughenedand catalyzed board (FIG. 4B).

Next, a resist pattern 21 for forming fine wirings is formed by alithography process (FIG. 4C). Then, an electrolytic plating film (finecopper wirings) 22 is formed over the nonelectrolytic copper-plated film20 where the resist pattern 21 is not formed (FIG. 4D).

Here, it is because the height (thickness) of the copper fine wiringsfrom the insulating resin board 2 a is made larger that the electrolyticplated film (fine copper wirings) 22 is formed over the nonelectrolyticcopper-plated film 20. This electrolytic plated film 22 can bring abouta good contacting state when the tip of the contact probe 100 comes intocontact with the object to be measured.

Next, the resist pattern 21 that becomes unnecessary is removed toexpose the copper fine wirings 22 (FIG. 4E). Then, the nonelectrolyticcopper-plated film 20 is removed by quick etching. At this time, thecopper fine wirings 22 are also slightly etched off at the same time(FIG. 4F).

Next, a resist pattern 21 is formed over the copper fine wirings 22 by alithography process to mask the copper fine wirings 22 (FIG. 4G). Then,an insulating layer 23 thinner than the copper fine wirings 22 is formedover the board by a coating method or a printing method using theinsulating resin material such as epoxy, BT resin, liquid crystalpolymer, or the polyimide, which is in a state of varnish dissolving ina solvent (FIG. 4H). The copper fine wirings 22 is nonelectrolyticgold-plated when necessary.

Next, the resist pattern 21 and the insulating layer 23 over the resistpattern 21 are dipped in the solvent, thereby being removed, whereby thefine lines are completed (FIG. 4I).

With the above-described process, a wiring pattern including the signalline 10 and the ground line 11 is formed on the insulating resin board 2a and then the board is cut at the final step, whereby the printedwiring board 2 is manufactured.

In this regard, in this embodiment, the line width of the contactelectrode (signal electrode 10 a, ground electrode 11 a) is 10 μm andthe pitch between the electrodes is 20 μm, but the line width can bearbitrarily selected when the printed wiring board 2 is manufactured.

However, a circuit pattern can be formed in a pitch of 10 μm or less bythe present semi-additive method (method of forming wirings by applyingthe copper plating to the insulating board) and hence it is preferablethat the contact electrodes (signal electrode 10 a, ground electrode 11a) be formed in an inter-electrode pitch of 10 μm or more.

Further, as for the pitch between the electrodes, to bring theabove-described good state of contact, it is preferable that the wholeof the nonelectrolytic copper-plated film 20 and the copper fine wirings22 be formed in a height (thickness) of from 5 μm to 20 μm.

Further, when both of the signal line and the ground line in a measuringpoint of the object to be measured are fine in the size of width, it isdifficult to position the tip of the contact probe 100 with highaccuracy and to put it at a correct position. In this case, it ispossible to put the contact probe 100 at a correct position with ease bydevising the shape of the electrode of the object to be measured.

For example, as shown in FIG. 5, a measuring pad 30 formed in the objectto be measured is constructed in such a way as to have the first bondingpad 30 a and the second bonding pad 30 b, which are respectively formedby printing, at the contact portion of the signal electrode 10 a and theground electrode 11 a of the contact probe 100.

For example, the first bonding pad 30 a with which the signal electrode10 a comes in contact is formed along the pitch between the signalelectrode 10 a and the ground electrode 11 a in a width t1 of 1.5 timesto 3 times as large as the pitch t2 between the electrodes. Further, thesecond bonding pad 30 b with which the ground electrode 11 a comes incontact is formed in a width t3 of 0.5 times or less as large as thepitch t2 between the electrodes. Still further, the pitch t4 between thefirst bonding pad 30 a and the second bonding pad 30 b is formed in asize of 0.5 times or less as large as the pitch t2 between theelectrodes.

Because the first bonding pad 30 a is formed in a large size in thismanner, its position can be easily found when it is observed by amicroscope. Hence, when a search is further made with attentionconcentrated on the contour line of the first bonding pad 30 a, a gapbetween the first bonding pad 30 a and second bonding pad 30 b can beeasily found. Further, because the first bonding pad 30 a is formed in awidth larger than the pitch t2 between the electrodes of the probe, whenthe tip (contact electrode) of the contact probe 100 is pressed onto themeasuring pad 30, even if it is slightly shifted in position, the tip ofthe contact probe 100 can be put into correct contact with the measuringpad 30. It is also possible to employ a construction in which the signalelectrode 10 a and the ground electrode 11 a are put into contact withthe second bonding pad 30 b and the first bonding pad 30 a,respectively.

As described above, according to the embodiment in accordance with thepresent invention, in the above-described contact probe 100, it ispossible to form the contact electrodes in an inter-electrode pitchbetween the electrodes is smaller than 50 μm on the above-describedprinted wiring board 2 and to put the tip of the probe onto the finepitch formed on the semiconductor integrated circuit, the package forthe semiconductor integrated circuit, printed circuit board, and thelike.

Therefore, it is possible to realize a high-speed high-frequencymeasurement on a fine pitch by mounting the above-described contactprobe 100 on the high-frequency measuring device.

Further, because the technology of manufacturing the printed wiringboard 2 is used, it is possible to form the pitch between the electrodesin a desired value with ease and high accuracy.

Embodiment

Next, a contact probe in accordance with the present invention will befurther described on the basis of an embodiment.

Embodiment 1

To study a contact probe in accordance with the present invention, acontact probe formed in the same construction as the above-describedembodiment was manufactured and a high-frequency characteristicsmeasurement test was conducted.

As an object to be measured was used a chip mounting package (board) 150having fine wirings of a width of 10 μm and a pitch of 20 μm and havinga differential pair strip line structure including two kinds of stripsof a long strip of 1.2 mm long and a short strip of 12.4 mm long. Itsplan view is shown in FIG. 6A and an A—A sectional view taken along aline A—A in FIG. 6A is shown in FIG. 6B, and an equivalent circuit ofits floating electric parameter is shown in FIG. 6C.

As shown in FIG. 6A, the chip mounting package 150 used for the objectto be measured has a ground pad GP and a signal pad SP, which arebonding pads, formed on its surface, and a ground line GL and a signalline SL are pulled out of these pads.

Further, as shown in FIG. 6B, the chip mounting package 150 has amultilayer wiring structure and insulating layers PI made of polyimideare laminated on a silicon board SS.

Still further, an equivalent circuit shown in FIG. 6C is such thatconsiders a parasitic capacitance Cs between a ground plane GN and asignal pad SP, a parasitic capacitance Cg between the ground plane GNand a ground pad GP, and the parasitic inductance Ls of the signal padSP, and the inductance Lg of the ground pad GP. Here, in this equivalentcircuit, a reference symbol G denotes a ground terminal and S denotes asignal terminal.

The tip of a contact probe 101 having the same construction as shown inthe above-described embodiment was pressed onto the wiring pattern ofthe object to be measured, for example, as shown in FIG. 7A andhigh-frequency characteristics were measured and evaluated by a timedomain reflectometry method (TDR).

Here, in the contact probe 101 in the drawing, a reference symbol Sdenotes a signal (electrode) and G denotes a ground (electrode).Further, a measurement was conducted on two kinds of long and shortdifferential pair strip lines of a strip line (short) of 1.2 mm long anda strip line (long) of 12.4 mm long.

The distribution of characteristic impedance as a measurement result isshown as a graph in FIG. 7B. In this graph, the time of the horizontalaxis corresponds to a position in a measuring line and a rising positionof a TDR waveform N of a standard voltage in a state where the tip ofthe probe is opened corresponds to the starting point of the measuringline.

In FIG. 7B, as shown as the results of the strip line (short) of 1.2 mmlong and the strip line (long) of 12.4 mm long, the distribution ofcharacteristic impedance of the line could be correctly measured andevaluated.

That is, it was thought that this was because the tip of the probe 101having a pitch of 20 μm was pressed onto a portion where the signal padSP and the ground pad GP (or ground line GL) were brought closer to eachother to a minimum pitch to prevent the effect caused by the parasiticinductance L and the parasitic capacitance C shown in the equivalentcircuit in FIG. 6C.

In this regard, the impedance of the line corresponding to the flatcenter portion of a waveform in the graph shown in FIG. 7B was evaluatedto be 55 ohm±11%.

COMPARATIVE EXAMPLE 1

A high-frequency characteristic measuring test was conducted by the useof a conventional contact probe 200 having a pitch of 250 μm. Here, theabove-described chip mounting package 150 was used as the object to bemeasured, just as with the case of the contact probe 101.

The tip of a contact probe 200 was pressed onto the pad portion of theobject to be measured, for example, as shown in FIG. 8A, andhigh-frequency characteristics were measured and evaluated by the timedomain reflectometry method (TDR).

Here, in the contact probe 200 in the drawing, a reference symbol Sdenotes a signal (electrode) and G denotes a ground (electrode).Further, a measurement was conducted on one of two kinds of long andshort differential pair strip lines of a strip line (short) of 1.2 mmlong and a strip line (long) of 12.4 mm long.

The distribution of characteristic impedance as a measurement result isshown as a graph in FIG. 8B. As shown in this graph, the distribution ofthe characteristic impedance of the line could not correctly measuredand evaluated as compared with the graph shown in FIG. 7B.

That is, it was thought that this was because the effect of theparasitic inductance L and the parasitic capacitance C prevented thecomponent of a TDR signal of high speed (over GHz) from reaching themeasuring line to cause a shortage of positional resolution.

From the above results of the embodiment, it was determined thathigh-speed high-frequency measurement at fine pitches of 20 μm, whichwas smaller than 50 μm, could be correctly conducted in thesemiconductor integrated circuit, the package for the semiconductorintegrated circuit, the printed circuit board, and the like by the useof the contact probe in accordance with the present invention.

1. A method of manufacturing a contact probe used for measuring andevaluating high-speed high-frequency characteristics, the methodcomprising the steps of: manufacturing a printed wiring board on whichwirings of a signal electrode and a ground electrode, which are put intocontact with an object to be measured, are formed; and electricallyconnecting the signal electrode to a core of a coaxial cable andelectrically connecting the ground electrode to an outer coveringconductor of the coaxial conductor, wherein in the step of manufacturingthe printed wiring board, an inter-electrode pitch between the signalelectrode and the ground electrode is formed in a size of from 10 μm ormore to less than 50 μm.
 2. The method of manufacturing a contact probeaccording to claim 1, wherein the step of manufacturing a printed wiringboard comprises the steps of: roughening and catalyzing a surface of aninsulating resin board; forming a nonelectrolytic copper-plated filmover the whole surface of the roughened and catalyzed board after thestep; forming a resist pattern for forming a fine wiring by alithography process after the step of forming the film; forming anelectrolytic copper-plated film on the nonelectrolytic copper-platedfilm, on which the resist pattern is not formed, after the step offorming a resist pattern for forming a fine wiring; removing the resistpattern after the step of forming an electrolytic copper-plated film toexpose the nonelectrolytic copper-plated film and the electrolyticcopper-plated film, which become copper fine wirings; and etching off anunnecessary nonelectrolytic copper except for the copper fine wiringsafter the step of removing the resist pattern.